Steering gear



A. J. DAWSON STEERING GEAR Oct. 25, 1938.

Original Filed Aug. 20, 1935 2 Sheets-Sheet l mvENToR f BY 0 1 i ATTORNEYE l m\ E.

Oct. 25, 1938.

` A. J. DAWSON STEERING GEAR Original Filed Aug. 20, 1956 Z'Sheets-Sheet 2 i3 ATTORNEm Patented Oct. 25, 1938k i y. y

UNITED; STATES PATENT OFFICIEL,V .i ,12,134,399

STEERING GEAR n ,Albert J. Dawson, Sewickley, Pa..' Continuation 'of applicationl Serial No. 97,022,

August 20, 1936; This application January 14, 1938, Serial No. 185,032

l z oiaims (o1. ao-52) v n This application is a continuationof applica- I, I, 2, 2, equipped with tillers 3, 3, Il, 4, may be tionSerial No. 97,022, filed August 20, 1936, on understood to be carried -by a single boat, and to Steering gear.V v 4be rotated, `pair by pair, in unison to effect My invention relates to the steering of Ships, steering. 7 v Y 15 and consists in refinements in `apparatus for For the two pairs of tillers two steering-rams 5 powerfully swinging the rudders.- A5,16 are provided, one for each pair, andthe Ship-steering apparatus has been built and Vassembly is such that as the piston of the steerused hitherto in which, associated with a hying ram is shifted the tillers associated with it draulic ram, areservoir of ram-operating liquid are swung. The rams are hydraulic. y

l10 is provided, and, associated with the reservoir, Referring to Fig. III, arotary screw pump 1, 10 a motor-driven pump. The pump and its motor constantly driven by a motor 8, constantly circuoperate continuously, and liquid supplied by the lates a- -ram-operating liquid (ordinarily oil)` reservoir is circulated between the outlet and through a azz'irculation system, lfrom exit 9 to inlet of the pump. In this line of liquid circulaintake*VV I0. In the circulation sys-tem a valvetion a valve-chest is arranged, and in such chest Chest IlI is included; from the valve-chest ycon- 13 a valve, responsive to the helm of the ship, is nections I2 and.I3 extend to the ends of the movable to either side of a neutral position. In cylinder of the ram 5; and within Vthe valvethe neutral position of the valve the line of liquid chest a valvev 'Il is arranged.k The valve-chest is circulation is open, and communication between a cylinder with ported Walls, the valve consists the opposite ends of. the ram and the pump is of a setV ofdiscsf mounted at properly spaced 20 cut off. When the valve is shifted to one side intervalsjupon Va common'stern, and the valve of the neutral position orthe other, the pump Structure is :movable longitudinally within the delivers liquid under pressure to one end of the cylllde"` i ISSDOH'S@ t0" the vWill `Of the PilOl- In ram or the other, and removes liquid from the Fig. III-the-valve is-shown in lneutral position,

`opposite end; the plunger of the ram is shifted and it will be perceived'that the pump is effective 25 (one way or the otheraccording as the valve -is Yto circulate liquid through the system, in a line shifted), and the rudder of the ship is power- 'of flow indicated by arrows. When thevalve Il fully turned to the port or the starboard, dependis in this' neutralposition there vis no hydraulic ing upon whichway the ram moves.v connection' to cylinder 5. `It will further be per- In the operation of such known apparatus it ceived that-,if the valve Il be shifted in either 30 has been foundthat the rudders are no-t deli'- direction from the position of Fig. III, a line of cately responsive to the helm. Whenfthe valve flow will be 'opened' through a branch I5v and is shifted from neutral position there is amo- Valve-'chest I'I to one of theconnections I2 and mentary wait before the pump builds up adequate I3, while th other connection (I3 or I2) will be operating pressure in the liquid delivered to the brought into outflow communication through 35 ram, and during such interval of lag the rudder, valve-chest' II with a branch I6. And 'at the subject to stress, tends to turn in retrograde same time the directline'ofcirculation lthrough direction. the Valve chest (that indicated by arrows in Fig.

The object of my invention is to provide ship- III) will be cut off. l I -40 steeringapparatus which is more minutely re- VMore specifically, if the valve I4` be shifted 40 sponsive tothe helmfand in which such retroin upward direction, as viewed in Fig. III, disc d grade motion of the rudder is substantially elimiofthe valve, rising', will close a lead a and cut off nated. The invention consists in refinement and the line of direct communication between diselaboration -of apparatus of the sort described charge line 9 and return line' I6; disc f will open 45 above. f Y ,v `l aline. of communication from branch I5 to lead '45 In the 'accompanying drawings'Fig. I is a dia- VI2 ofthe ram;v and discus( will open a line of grammatic view in plan and section ofthe steercommunication from lead I3 o f the ram to a lead ing apparatus of a dredge boat in which the in- 'c opening into return line I6.v If the valve I4 vention has been embodied; Fig. II is a viewto be shifted in downward direction, thev disc e of 5 0 larger scale, showing in axial section the control the valve will c ut off "communication between V50 valve which, responsive to the will of the pilot, 'discharge line! and the lead a of return line I6; renders the apparatus effective; and Fig. III is the line of. flow from the pumpwill be opened a fragmentary View, tolarger scale than Fig, I, from lead I5 to -leadlwhile the lead fl! will be .affording fuller illustration oicertain parts. brought i-ntoc'oinmuiiication with a lcad'b open- Referring to Fig. I, `two pairs of rudder-posts inginto'returri-lineI6.I 'Ihus'gwhile one end'of i5 (Fig. I) are interconnected by a line |10 that communicates through a lead I1I with a sumptank I8 including a supply of. the ram-operating4 liquid. The liquid-circulating system` of each ram assembly may drain into the sump-tank, and, by the action of the pumps, the system may be filled with which, collecting and standing in the ends of the valve-chest, would otherwise oppose theshifting of thevalves. ,f

Fig. II is a working. drawing of ,the valve-chest structure; to it reference numerals and arrows have been added, and these, taken -with thediagrammatic showing of Fig. III, Will make structure and operation plain.

The apparatus of the invention is provided with-a line I9. of communication from the main line of liquid circulation, at a point between the outlet of the pump 1 and the valve-chest I I, to the tank I 8; in this line of communication a pressure relief valve 22 and an airr chamber 20 are included, and the relief valve, normally standing in closed position, opens only when a pressure of critical value (sayw3`50 pounds) is attained..V l i A second and smaller screw pump 23, also .constantly driven by motor 8, lisrin constantly open communication with the supply tank I8. Pump 23 delivers a stream of liquid toa pipe 24, whence there is a double line of flow.. One line is a line 25 of return flow to theintake side of the pump `23, and the other line is a line of delivery to the circulating stream that pump 1 impels from outlet 9 to inlet I0, and on4 the delivery side of the valve-chest I I.` vIn the line 25 of `return flow is a relief valve 21 that opens-only .when a critical pressure of less value than thevcritical :pressure of relief valve 22 is attained-in this case a pressure of 200 pounds.L Under theinfluence of pump 23 the body of liquid that idly, circulates, when the valve I4 is in the position shownvin Fig. III, is maintainedunder a pressure equal to the critical value (200 pounds) fixedby the valve 21. TheA relief valve 22, only opening .at a critical pressure of 350 pounds,rremainsvclosed while the liquid is in this manner idly circulated.

At alltimes, exceptywhen the pressure of the circulating stream Aof pump 1 falls below 200 pounds (such as occurs when the valve I4 is in course of being shifted) the relief valve 21 stands in open position and the pump 23 is eifective to circulate oil through returnlline 25. The pressure that then is effective in circulating the oil through return line 25 equalsV the margin Vby which the pressure generated .by` pump.23 exceeds said critical pressureof valven21. Itwill be understood, therefore, thatwhen valve I4 is shifted andthe direct line vtween theloutlet lead 9 ofpump 1 and the return lead I 6 is blanked (as already described) a pressure of substantially 200 pounds isximmediately Veffective upon that -end of the ram to which lead ,I5-opens. f Simultaneously, communication is "openedfrom the opposite end oftheram, through movement. Wait until the pump 1 builds up the pressure of I the liquid to ram-operating value-an eiective liquid from ,the tank.. f 'flhe pipe' connection I1 provides escape for the gas or oil.

of Acommunication be- 2,184,399 .f a .v branch I 6, to the inlet of the pump 1. And, while l it is true that lead 26 opens to the return branch I6, the capacity of the pump 23 is so much lower than the capacity of pump 1 and the rate of discharge of pump 23 is so far below the rate of intake of pump 1, that the 200-pound pressure normally prevailing in branch I6 is immediately dissipated. Thus the pressure constantly maintained by pump 23 becomes effective when valve I4 is shifted to hold the ram from retrograde There is no momentary relief or pressure differential between the opposite sides A of the ram is instantly obtained and held throughout the range of operation. Thus it is that the rudder, which might otherwise respond f vto retrograde turning stress when the valve I4 is in Vcourse of being shifted, is positively held in-position, ready when the shifting of valve I4 is completed to respond to the steering apparatus. Retrograde turning is resisted `and prevented.

Assuming for purposes of explanation that pump 23I and its connections are eliminated, when the-.valve I4 is shifted from the inactive or neutral position shown in Fig. III of the drawings to a position in which the pump delivers to cylinder 5 at one end and cylinder 5 at the opposite end delivers to the intake of the pump 1, then the power of the pump 1 is exerted to shift the piston within cylinder 5, and to retain it at the limit of its traverse. When that limit has been reached, the oil ceases to circulate, and under the influence of the pump 1 the pressure of the liquid between the outlet of the pump and the power end of the ram immediately rises above the normal value of 200 pounds set by relief valve 21. The pressure rises until the critical pressure (350 pounds) of relief valve 22 is reached, whereupon such relief valve opens and the liquid dei erating powerfully to maintain the parts in the positions to which they have come.

The two relief valves 22 and 21, with the pumps 1 yand 23 and their connections, have the effect of maintaining the stream of oil that circulates, while the valve I4 is in neutral position, at a predetermined pressure of 200 pounds. This pressure of 200 poundsis like a spring, effective, when the valve I4 is Vin course of shrifting, to prevent'retrograde turning of the rudder, and it is in virtue of the fact that the power exerted by pump 1 exceeds that exerted by pump 23 that, when the valve I4 has come to the limit of its shift on either side of neutral position, the pump 1V has capacity immediately to increase the effective vpressure of the liquid to a value above the normal value of 200 pounds; that is, to a value upward to but not in excess of a maximum value of 350 pounds (the criticalpressure at which the relief valve22 opens), whereby the ram is instantly responsive to the shift of the valve I4.

In the steering of a boat 'the valve I4 is shifted, held for agreater orV less interval of'time, and returned to neutral position. According to the length of time that the valve is retained in shiftedaside position, the rudders are swung more widely :to left or right, and the direction of swing is in` accord with the direction in which valve I4 is shifted. From yswung-aside position the rudders may be returned,to'neutral+that is to say, foreand-aft-position by the opposite shifting of valve I4.

The pump 23 serves, in addition to the functions already described, to feed oil from the tank i8 to the branch I6, in such quantities as to make up for the return flow to the tank I8 while the relief valve 22 is open and for losses due to leakage in the system.

When the system is to be drained, the normally closed valve 2I is opened and communication established between branch I6 and the tank I8, and pet-cocks 30, arranged in usual way in the system, are opened to the outer atmosphere. The oil drains from the system into the tank I8. Again, when the system is to be lled, the valve 2I and pet-cocks 30 being open, the pumps 1 and 23 are set in operation. While the pumps are charging in oil from the tank I8, the valve I4 is shifted first to one end of its range of movement and then to the other, thus reciprocating the ram and insuring that all parts of the system are fully charged. Then the valve 2l and pet-cocks are closed and the apparatus is ready for service.

Oil lters or strainers 28 are included at convenient and suitable points in the pipe connections of the system.

I claim as my invention:

l. Steering apparatus including a rudder, a steering ram, a valve-chest, leads for ram-operating liquid between the valve-chest and the opposite ends of the ram, a reservoir of liquid, a line of liquid circulation including said valve-chest, a continuously operating high-capacity pump in said line of circulation, a line of communication between said line of circulation (at a point between said valve-chest and the outlet of the pump) and said reservoir, a high-pressure relief valve in said line of communication, means for imposing augmented pressure, of less value than the critical pressure of said high-pressure relief valve, on the liquid in'said line of circulation, said means including a low-capacity pump adapted to deliver liquid into said line of circulation at a point between said valve-chest and the inlet of said high-capacity pump, a line of return flow between the delivery and intake sides of said lowcapacity pumpa low-pressure. relief valve in said line of return flow, and a valve vin said valve-chest movable between a position in which said line oi liquid circulation is openand communication between the pumps and the opposite ends of the ram is cut off, and a position in which said line of circulation is interrupted and communication between the high-capacity pump and the leads to the ends of the ram is established. Y

2. Steering apparatus including a rudder, a steering ram, a valve-chest, leads for ram-operating liquid between the valve-chest and the opposite ends of theV ram, a reservoir of liquid, a line of liquid circulation including said valvechest, a continuously operating main pump in said line of circulation, a high-pressure relief valve connected to the line of delivery of -said main pump, means for imposing augmented pressure, of less value than the critical pressure of said high-pressure relief valve, onthe liquid in said line of circulation, said means including an auxn iliary pump adapted to deliver liquid into said line of circulation at a point between said valvechest and the inlet of said main pump and a lowpressure relief Valve on the delivery side of said auxiliary pump, movable between a position in which said line of liquid 'circulation tween the pumps and a valve in said valve-chest is open and communication beand the opposite ends of the` ram is cut off, and a position in which said line 'y of circulation is interrupted and communication is established between the main pump and the leads to the ends of the ram.

' ALBERT J. DAWSON. 

